Engine spark timing control

ABSTRACT

The ignition timing includes a distributor having a vacuum controlled servo actuator to advance the timing as a function of changes in carburetor spark port vacuum, the servo normally spring biasing the distributor towards a minimum advanced or retarded timing position; the vacuum line from the spark port including a device that is operative (1) during light vehicle accelerations to delay the spark advance by delaying vacuum application to the servo, (2) during heavy accelerations to immediately retard the ignition timing by transferring the higher spark port pressure signal directly to the servo; (3) to provide an immediate retarded ignition timing during vehicle decelerations by directly communicating spark port pressure level to the servo; (4) to provide immediate return of the timing to an advance setting after momentary decelerations by again directly connecting the spark port pressure level to the servo; and, (5) to provide normal spark advance during cold weather operation by directly connecting the spark port vacuum to the servo; the above providing low emissions and good vehicle performance during all operating engine conditions.

United States Patent [191 Vartanian ENGINE SPARK TIMING CONTROL [75]Inventor: Richard D. Vartanian, Dearbom,

Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Feb. 2, 1972 [21] Appl. No.: 222,886

Gropp ..l23/l 17 A Primary Examiner-Laurence M. Goodridge AssistantExaminer-Cort Flint Attorney-Keith L. Zerschling et al.

[451 May 1, i973 [5 7] ABSTRACT The ignition timing includes adistributor having a vacuum controlled servo actuator to advance thetiming as a function of changes in carburetor spark port vacuum, theservo normally spring biasing the distributor towards a minimum advancedor retarded timing position; the vacuum line from the spark portincluding a device that is operative (1) during light vehicleaccelerations to delay the spark advance by delaying vacuum applicationto the servo, (2) during heavy accelerations to immediately retard theignition timing by transferring the higher :spark port pressure signaldirectly to the servo; (3) to provide an immediate retarded ignitiontiming during vehicle decelerations by directly communicating spark portpressure level to the servo; (4) to provide immediate return of thetiming to an advance setting after momentary decelerations by againdirectly connecting the spark port pressure level to the servo; and, (5)to provide normal spark advance during cold weather operation bydirectly connecting the spark port vacuum to the servo; the aboveproviding low emissions and good vehicle performance during alloperating engine conditions.

14 Claims, 1 Drawing Figure Patented May 1, 1973 Y 3,730,154

ENGINE SPARK TIMING CONTROL This invention relates, in general, to anengine spark timing control system. More particularly, it relates to oneproviding a delayed spark advance during normal vehicle accelerations,with a quick spark timing recovery after momentary decelerations, and abypass of the spark timing control to provide normal spark advance forcold weather performance operation.

This invention is an improvement upon the spark timing control devicesshown in U.S. Ser. No. 59,500, Engine Spark Timing System, Richard D.Vartanian, filed July 30, I970, now U.S. Pat. No. 3,678,907, and U.S.Ser. No. 60,489, Engine Spark Timing Control System, Karl H. Gropp,filed Aug. 3, 1970, now U.S. Pat. No. 3,698,366, all having a commonassignee. The device shown in Ser. No. 59,500 delays spark advanceduring normal light vehicle accelerations while providing immediatemaximum retarded timing during heavy vehicle accelerations; and, it hasa vacuum reservoir that provides a quick recovery from a retardedsetting back to a normal spark advance setting, after momentary vehicledecelerations, to improve emission as well as performance levels.

The device shown in Ser. No. 60,489 controls the engine spark timing bydelaying the advance during normal light vehicle accelerations, and alsodelays movement of the timing toward a retarded setting during vehicledecelerations; it further quickly retards the timing during heavyvehicle decelerations; and, provides a quick recovery of the timing to anormal advanced setting after momentary decelerations.

The invention provides the advantages of the two above describeddevices, and in addition provides a control of the engine spark timingfor cold weather operation to provide better emission and performanceoperation. More particularly, the invention consists of a device locatedbetween the carburetor spark port and distributor servo that not onlyslowly advances the spark timing during normal light vehicleaccelerations, quickly moves the timing into a maximum retarded settingduring heavy vehicle accelerations, and provides a quick recovery of thetiming to an advanced setting after momentary decelerations; but alsoprovides good cold weather operation by providing normal spark advancebelow a predetermined temperature level by rendering ineffective theother controls at this time.

It is an object of the invention, therefore, to provide an engine sparktiming control that combines all of the features described above into asingle device located between the carburetor and the engine distributorservo actuator to reduce emission output while at the sametime providegood performance during all engine operating conditions.

It is another object of the invention to provide an engine spark timingcontrol system that includes a device located between the enginecarburetor and distributor that (I) automatically slowly advances theengine spark timing during normal light vehicle accelerations; (2)quickly retards the engine timing during engine decelerations and heavyengine accelerations; (3) quickly returns the spark timing towards anormal advanced setting subsequent to momentary vehicle decelerations;and, (4) provides a normal spark advance of the timing for cold weatheroperation below a predetermined temperature by rendering the spark delayand other portions of the device ineffective.

Other objects, features and advantages of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawing wherein the figure illustrates schematically a crosssectional view of an engine ignition timing control system embodying theinvention.

The figure shows, schematically, only those portions of an internalcombustion engine that are normally associated with the enginedistributor spark timing setting control; such as, for example, acarburetor 10, a dis tributor breaker plate 12, a vacuum servo 14 tocontrol the movement of breaker plate 12, and a line 16 connectedbetween the carburetor and vacuum servo to automatically change theengine spark timing setting as a function of changes in engine sparkport vacuum.

More specifically, carburetor 10 is shown as being of the downdraft typehaving the usual air-fuel induction passage 18 with an atmospheric airinlet 20 at one end and connected to the engine intake manifold 22 atthe opposite end. Passage 18 contains the usual fixed area venturi 24and throttle valve 26. The latter is rotatably mounted on a part of thecarburetor body across passage 18 in a manner to control the flow ofair-fuel mixture into the intake manifold. Fuel would be inducted in theusual manner from a nozzle, not shown, projecting into or adjacentventuri 24, in a known manner.

Throttle valve 26 is shown in its engine idle speed position essentiallyclosing induction passage 18, and is rotatable to a nearly verticalposition essentially unblocking passage 18. A spark port 28 is providedat a point just above the idle position of throttle valve 26, to betransversed by the throttle valve during its part throttle openingmovements. This will change the vacuum level in spark port 28 as afunction of the rotative position of the throttle valve, the spark portreflecting essentially atmospheric pressure in the air inlet 20 uponclosure of the throttle valve. An intake manifold vacuum sensing port 30is also provided, for a purpose to be described.

As stated previously, the distributor, includes a breaker plate 12 thatis pivotally mounted at 31 on a stationary portion of the distributor,and movable with respect to cam 32. The latter has six peaks 34corresponding to the number of engine cylinders. Each of the peakscooperates with the follower 36 of a breaker point set 38 to make orbreak the spark connection in a known manner for each one-sixth, in thiscase, rotation of cam 32. Pivotal movement of breaker plate 12 in acounter-clockwise spark retard setting direction, or in a clockwisespark advance setting, is provided by an actuator 40 slidably extendingfrom vacuum servo 14.

Servo 14 may be of a conventional construction. It has a hollow housing42 whose interior is divided by an annular flexible diaphragm 48 into anatmospheric pressure chamber 44 and a vacuum chamber 46. The diaphragmis fixedly secured to actuator 40, and is biased in a rightward retarddirection by a compression spring 50. Chamber 44 has an atmospheric orambient pressure vent, not shown, while chamber 46 is connected by abore, not shown, to line 16.

During engine-off and other operating conditions to be described,atmospheric pressure exists on both sides of the diaphragm 48,permitting spring 50 to force the actuator 40 to the lowest advance or aretarded setting position. Application of vacuum to chamber 46 movesdiaphragm 48 and actuator 40 toward the left to an engine spark timingadvance position, by degrees as a function of the change in vacuumlevel.

Turning now to the invention, the vacuum line between the spark port 28and line 16 of the servo contains a control device 60 having a hollowcasing 62. The casing has three outlets 64, 66 and 68, outlet 64 beingconnected by a line 70 to spark port 28; outlet 66 being connected toline 16, and outlet 68 being connected by a line 72 to the manifoldvacuum port 30.

Housing 60 contains a first rigid partition member 74 dividing thecasing into two chambers 76 and 78 and separating the two lines 70 and16. The partition 74 contains a number of openings permitting controlledcommunication between the chambers 76 and 78. The openings include asintered metal orifice 80, a one-way umbrella type check valve 82 and anunrestricted passage 84. The sintered metal orifice 80 permits only slowcommunication of the pressure levels between chambers 76 and 78, and aswill be seen later, permits only a slow or delayed spark advance withincreases in thevacuum in spark port 28. The one-way check valve 82 isof a conventional construction and is unseated when the pressure levelin chamber 76 exceeds that in chamber 78 to quickly communicate thepressure levels between lines 64 and 66, bypassing the sintered metalorifice 80. The unrestricted line 84 is a further bypass betweenchambers 76 and 78 to at times permit free communication of pressurelevels between chambers 76 and 78, as will be described.

The wall of chamber 78 remote from the partition 74 is defined by anannular flexible diaphragm 86 that is biased by a spring 88 to theposition shown seated against the open end of passage 84 to block it.The diaphragm thus in effect is a valve seating and unseating againstthe open end of the conduit 84 to permit or block free communication ofthe pressure levels between chambers 76 and 78. The force'of spring 88is chosen so that it will maintain the diaphragm in the position shownblocking line 84 in all operative conditions of the engine except duringdecelerating operations when the manifold vacuum level in line 72reaches a high value, such as, for example, over 21 inches Hg.

Completing the construction, a bimetallic temperature responsive element92 is secured in the device 60 adjacent the passage 84 and the diaphragm86. The characteristics of the bimetal 92 are such that its outwardlyprojecting arms 94 are in the position shown below a predeterminedambient temperature level so as not to interfere with the operation ofthe device above this predetermined temperature. However, below thetemperature, for cold weather operation, the arms 94 will move upwardlyin response to temperature decreases until the desired temperature levelis reached, at which point the arms will move the diaphragm 86 upwardlyto the dotted line position 96 off the end of the conduit 84 toimmediately provide direct communication between chambers 76 and 78.

Thus, at this time, the spark timing will be advanced as a directfunction of the level of vacuum in the spark port 28 regardless of theeffect of the sintered metal orifice 80, the check valve 82, or thevacuum in the manifold 22. In other words, for cold weather performanceoperation, the bimetal 92 renders ineffective all of the other controlscontained in device 60 and provides advance and retard of the sparktiming as if the device 60 were not in the line 16 at all.

In operation, prior to starting the engine, servo chambers 44 and 46 areequalized at atmospheric or ambient pressures, and, therefore, the sparktiming is conditioned for a maximum retarded setting, for startingpurposes.

When the engine is started and begins running, the closed throttleposition shown provides essentially an atmospheric pressure level inspark port 28, and, therefore, the spark timing remains retarded. Uponopening the throttle valve for providing light normal vehicleaccelerations, the manifold vacuum level reflected in spark port 28 andchamber 76 is communicated slowly to chamber 78 and servo line 16through the sintered metal orifice 80. The check valve 82 is seatedbecause of the higher pressure level in chamber 78. The line 84 remainsclosed since the force of spring 88 is overcome only during vehicledeceleration operation providing the high vacuum level necessary toovercome the spring force. Accordingly, the servo diaphragm 48 is slowlymoved leftwardly to slowly advance the spark timing.

If now the throttle is suddenly moved wide open indicating heavy vehicleaccelerations, and assuming some if not maximum spark advance hasalready been provided by this time, the sudden decay of vacuum at thespark port 28 reflected in chamber 76 provides a higher pressure leveltherein as compared to that in chamber 78 to thereby unseat check valve82 and immediately reflect the pressure level at the spark port to servovacuum chamber 46. This permits spring 50 to stroke the actuator 40 tothe right to immediately move the spark timing breaker plate to retardthe timing. The timing will then advance from the retarded setting as afunction of the subsequent increase in manifold vacuum in spark port 28as the vehicle accelerates and the throttle valve 26 is slowly backedoff towards its closed position.

Now if the throttle valve is suddenly returned to the position shown,the pressure level at the spark port will be essentially atmospheric.With the engine decelerating, however, the manifold vacuum level at port30 and in chamber will be quite high and sufficient to overcome theforce of spring 88 and open the passageway 84. This provides immediatecommunication of atmospheric pressure in spark port 28 to servo chamber46 and provides an immediate stroking of the breaker plate to a maximumretarded setting. This is desirable to reduce emissions by providinglater burning and lower combustion temperatures and pressures.

If after a momentary deceleration, the vehicle is again accelerated byopening throttle valve 26, since it takes approximately five seconds forthe vacuum in the manifold to decay to the level of the pressure at thespark port, the vacuum in chamber 90 will maintain diaphragm 86 unseatedfrom conduit 84. Simultaneously, however, the vacuum at the spark port28 is communicated through chamber 76 and line 84 to line 16 toimmediately stroke the breaker plate to essentially the same advancedsetting that it had prior to the deceleration. it will be seen,therefore, that reacceleration after a momentary deceleration provides aquick recovery of the advance setting due to the construction of thedevice 60.

Finally, when the temperature level drops below a predetermined value,the bimetal 92 will at this time have moved the diaphragm 86 upwardly toprovide direct communication between chambers 76 and 78. Accordingly, solong as the temperature remains below the predetermined chosen level,advance and retard of the engine timing will be maintained solely as afunction of the changes in spark port vacuum in spark port 28.

From the above, it will be seen that the invention provides in onedevice all of the engine spark timing controls desired to providereduced emissions while at the same time provide performance. It willalso be seen that the invention provides a device that only providesslow advance during normal light vehicle accelerations, quickly retardsthe spark timing during heavy vehicle accelerations and decelerations,and provides a quick recovery of the system toward a normally advancesetting after momentary vehicle decelerations, but also provides goodcold weather operation by rendering ineffective the above describedcontrols and permitting spark advance and retard solely as a function ofthe changes in spark port vacuum and throttle valve position.

While the invention has been described and illustrated in its preferredembodiment, it will be clear to those skilled in the arts to which itpertains that many changes and modifications may be made thereto withoutdeparting from the scope of the invention. For example, it will be clearthat while a single diaphragm distributor servo actuator 14 is shown,the invention is equally applicable to one using a dual diaphragmdistributor servo actuator such as, for example, is fully shown anddescribed in FIG. 2 of US. Pat. No. 3,599,614, Kittredge, Dual DiaphragmDistributor, where line 16 could be connected to the primary or advancechamber of the servo shown therein.

I claim:

1. An engine spark timing control system comprising, an enginecarburetor having an induction passage containing a spark port locatedabove the idle speed position of a throttle valve controlling flowthrough the passage and subject to the change in vacuum in the inductionpassage as a function of the movementof the throttle valve from its idlespeed position, an engine distributor having a breaker plate springbiased to a retarded spark timing position and being pivotally movablein opposite directions to advance and retard the spark timing, vacuumcontrolled servo means connected to the breaker plate for moving thesameto advance the timing as a function of vacuum applied to the servomeans, conduit means connecting the spark port and servo means, and flowrate control means in the conduit means to control the rate of change ofapplication of vacuum from the spark port to the servo means, saidcontrol means including first flow rate delay means operable in responseto a gradual opening of the throttle valve for light engine acceleratingoperation to slowly apply vacuum to the servo means to move the breakerplate in the advance spark direction at a slower rate than wouldnormally be effected for the vacuum signal present at the spark port,and second means.

operable in response to closing of the throttle valve effecting adecelerating operation to immediately equalize the pressure levels atthe spark port and servo means to immediately lower the spark timingtowards a 2. A spark timing control as in claim 1, the second meansbeing operable by engine intake manifold vacuum above a predeterminedlevel.

3. A spark timing control as in claim 1, including temperatureresponsive means to render both first and second means ineffective attimes to permit advance and retard of the spark timing setting solely asa function of the change in throttle valve movement and spark portvacuum.

4. A spark timing control as in claim 1, the second means including anadditional flow connection in the conduit means between the spark portand servo means bypassing the first means.

5. A spark timing control as in claim 1, the first means comprising aflow restriction and a one-way check valve in parallel flow pathsbetween the spark port and servo means, the check valve unseating inresponse to a higher pressure level at the spark port than at the servomeans.

6. A spark timing control as in claim 5, the second means including afurther flow connection in the conduit means between the spark port andservo means in a parallel flow relationship to the flow restriction andthe check valve.

7. A spark timing control as in claim 4, including valve means movableto block and unblock the additional flow connection.

8. A spark timing control as in claim 6, including valve means movableto block and unblock the further flow connection.

9. A spark timing control as in claim 8, including manifold vacuum meansto move the valve means to an unblocking position, and spring meansbiasing the valve means to a blocking position.

10. A spark timing control as in claim 8, the second means including asecond servo having an actuator spring biased to block the further flowconnection and movable by manifold vacuum applied thereto to unblock thefurther flow connection.

11. A spark timing control as in claim 9, including temperatureresponsive means moving the valve means to an unblocking position belowa predetermined temperature to render the flow restriction and checkvalve ineffective.

12. A spark timing control as in claim 1, the control means including adevice located in the conduit means and having a hollow housing havingfirst and second and third outlets connected respectively to the sparkport and servo means and to manifold vacuum, the housing havingpartition means dividing the housing into a first chamber connected tothe spark port first outlet, and a second chamber connected to the servomeans second outlet, the partition. means containing a number ofpassages including a flow restriction constituting the delay means and aone-way check valve and another passage forming a part of the secondmeans for communicating flow between the chambers, and an annularflexible diaphragm defining a wall of the second chamber and a thirdchamber connected to the manifold vacuum outlet, and spring meansbiasing the diaphragm to seat against the another passage to normallyblock the same, manifold vacuum above apredetermined level in the thirdchamber moving the diaphragm to unblock the another passage and directlyconnect the port pressure level to the servo means.

13. A spark timing control system as in claim 12, including temperaturesensitive means movable against the diaphragm below a predeterminedtemperature to unblock the another passage.

14. An engine spark timing control system comprising, an enginecarburetor having an induction passage containing a spark port locatedabove the idle speed position of a throttle valve controlling flowthrough the passage and subject to the change in vacuum in the inductionpassage as a function of the movement of the throttle valve from itsidle speed position, an engine distributor having spark timing controlmeans spring biased to a retarded spark timing position and beingmovable in opposite directions to advance and retard the spark timing,vacuum controlled servo means connected to the control means for movingthe same to advance and retard the timing as a function of vacuumchanges applied to the servo means, conduit means connecting the sparkport and servo means, and flow rate delay means in the conduit means toslow the rate of change of application of vacuum from the spark port tothe servo means, said delay means being operable in response to gradualchanges in spark port vacuum level below a predetermined differentialchange upon change in position of the throttle valve to move the breakerplate in the advance spark direction at a rate slower than wouldnormally be effected as called for by the vacuum signal present at thespark port, and temperature responsive means operable below and inresponse to the attainment of a predetermined temperature level tobypass the delay means to provide cold weather spark timing changesconcurrent with and as a function of changes in spark port vacuum leveland independent of the flow rate delay means.

I I i II l

1. An engine spark timing control system comprising, an enginecarburetor having an induction passage containing a spark port locatedabove the idle speed position of a throttle valve controlling flowthrough the passage and subject to the change in vacuum in the inductionpassage as a function of the movement of the throttle valve from itsidle speed position, an engine distributor having a breaker plate springbiased to a retarded spark timing position and being pivotally movablein opposite directions to advance and retard the spark timing, vacuumcontrolled servo means connected to the breaker plate for moving thesame to advance the timing as a function of vacuum applied to the servomeans, conduit means connecting the spark port and servo means, and flowrate control means in the conduit means to control the rate of change ofapplication of vacuum from the spark port to the servo means, saidcontrol means including first flow rate delay means operable in responseto a gradual opening of the throttle valve for light engine acceleratingoperation to slowly apply vacuum to the servo means to move the breakerplate in the advance spark direction at a slower rate than wouldnormally be effected for the vacuum signal present at the spark port,and second means operable in response to closing of the throttle valveeffecting a decelerating operation to immediately equalize the pressurelevels at the spark port and servo means to immediately lower the sparktiming towards a retarded setting, the second means being effective attimes in response to a reaccelerating operation from the deceleratingoperation to render ineffective the first delay means and immediatelyequalize the spark port and servo means vacuum levels to restore thespark timing to a higher advance setting.
 2. A spark timing control asin claim 1, the second means being operable by engine intake manifoldvacuum above a predetermined level.
 3. A spark timing control as inclaim 1, including temperature responsive means to render both first andsecond means ineffective at times to permit advance and retard of thespark timing setting solely as a function of the change in throttlevalve movement and spark port vacuum.
 4. A spark timing control as inclaim 1, the second means including an additional flow connection in theconduit means between the spark port and servo means bypassing the firstmeans.
 5. A spark timing control as in claim 1, the first meanscomprising a flow restriction and a one-way check valve in parallel flowpaths between the spark port and servo means, the check valve unseatingin response to a higher pressure level at the spark port than at theservo means.
 6. A spark timing control as in claim 5, the second meansincluding a further flow cOnnection in the conduit means between thespark port and servo means in a parallel flow relationship to the flowrestriction and the check valve.
 7. A spark timing control as in claim4, including valve means movable to block and unblock the additionalflow connection.
 8. A spark timing control as in claim 6, includingvalve means movable to block and unblock the further flow connection. 9.A spark timing control as in claim 8, including manifold vacuum means tomove the valve means to an unblocking position, and spring means biasingthe valve means to a blocking position.
 10. A spark timing control as inclaim 8, the second means including a second servo having an actuatorspring biased to block the further flow connection and movable bymanifold vacuum applied thereto to unblock the further flow connection.11. A spark timing control as in claim 9, including temperatureresponsive means moving the valve means to an unblocking position belowa predetermined temperature to render the flow restriction and checkvalve ineffective.
 12. A spark timing control as in claim 1, the controlmeans including a device located in the conduit means and having ahollow housing having first and second and third outlets connectedrespectively to the spark port and servo means and to manifold vacuum,the housing having partition means dividing the housing into a firstchamber connected to the spark port first outlet, and a second chamberconnected to the servo means second outlet, the partition meanscontaining a number of passages including a flow restrictionconstituting the delay means and a one-way check valve and anotherpassage forming a part of the second means for communicating flowbetween the chambers, and an annular flexible diaphragm defining a wallof the second chamber and a third chamber connected to the manifoldvacuum outlet, and spring means biasing the diaphragm to seat againstthe another passage to normally block the same, manifold vacuum above apredetermined level in the third chamber moving the diaphragm to unblockthe another passage and directly connect the port pressure level to theservo means.
 13. A spark timing control system as in claim 12, includingtemperature sensitive means movable against the diaphragm below apredetermined temperature to unblock the another passage.
 14. An enginespark timing control system comprising, an engine carburetor having aninduction passage containing a spark port located above the idle speedposition of a throttle valve controlling flow through the passage andsubject to the change in vacuum in the induction passage as a functionof the movement of the throttle valve from its idle speed position, anengine distributor having spark timing control means spring biased to aretarded spark timing position and being movable in opposite directionsto advance and retard the spark timing, vacuum controlled servo meansconnected to the control means for moving the same to advance and retardthe timing as a function of vacuum changes applied to the servo means,conduit means connecting the spark port and servo means, and flow ratedelay means in the conduit means to slow the rate of change ofapplication of vacuum from the spark port to the servo means, said delaymeans being operable in response to gradual changes in spark port vacuumlevel below a predetermined differential change upon change in positionof the throttle valve to move the breaker plate in the advance sparkdirection at a rate slower than would normally be effected as called forby the vacuum signal present at the spark port, and temperatureresponsive means operable below and in response to the attainment of apredetermined temperature level to bypass the delay means to providecold weather spark timing changes concurrent with and as a function ofchanges in spark port vacuum level and independent of the flow ratedelay means.